Air valve pressure diaphragm carburetor

ABSTRACT

A carburetor having throttle and air intake valves and a booster venturi in both the primary and secondary air intake passages.

United States Patent Woods May 13, 1975 1 1 AIR VALVE PRESSURE DIAPHRAGM [56] References Cited CARBURETOR UNITED sTATEs PATENTS [76] Inventor: Stephen Woods, 311 Mason, Ann 2,031,379 2/1936 Mathieu 261/D1G. 39 Arbor, Mich. 48103 2,925,257 2/1960 Cohn 261/78 R 3,471,132 10/1969 Su1livan.. 261/78 R [22] Flledl 1974 3,648,988 3/1972 Dibert 261/D1G. 39 N I 4 3,664,648 5/1972 See1ey, Jr... 261/D1G. 39 [2]] Appl 33l96 3,715,108 2/1973 Denton 261/50 A R l t U. A D e f S FOREIGN PATENTS OR APPLICATIONS [63] Continuatlon-m-part of Ser. No. 335,550, Feb. 26,

1973 Pat. No 3,796,413, which is a 59,216 11/1924 Sweden 261/78 R continuation-in-part of Ser. No. 175,539, Aug. 27, 1971, abandoned, which is a continuation-in-part of Primary ExaminerTim R. Miles Ser. No. 846,563, July 31, 1969, Pat. No. 3,618,904, Attorney, Agent, or Firm-Whittemore, Hulbert & which is a continuati0n-in-part of Ser. No. 822,828, Bdk April 9, 1969, Pat. No. 3,556,067, which is a continuation-in-part of Ser. No. 629,488, April 10, 1967, abandoned. [57] ABSTRACT A carburetor having throttle and air intake valves and [52] US. Cl. 261/78 R; 261/D1G. 39 a booster venturi in both the primary and secondary [51] Int. Cl. F02m 19/08 air intake passages,

261 D1 .39,78R [58] Fleld of Search G 9 Claims, 7 Drawing Figures 1 251; J I 1 /f////// 204 AIR VALVE PRESSURE DIAPHRAGM CARBURETOR REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of my copending application Ser. No. 335,550, tiled Feb. 26, 1973, now US. Pat. No. 3,796,413, which application Ser. No. 335,550 is a continuation-inpart of my application Ser. No. 175,539, filed Aug. 27, 1971, now abandoned, which application Ser. No. 175,539 was a continuation-in-part of my application Ser. No. 846,563, filed July 31, 1969. and now US. Pat. No. 3,618,904, which application Ser. No. 846,563 was a continuation-in-part of my application Ser. No. 822,828, filed Apr. 9, 1969, and now US. Pat. No. 3,556,067, which application Ser. No. 822,828 was a continuation-in-part of my application Ser. No. 629,488, filed Apr. 10, 1967, and now abandoned.

SUMMARY OF THE INVENTION One object of this invention is to provide a carburetor designed to accurately control wide-open, partthrottle and idle fuel and air requirements.

Another object is to provide a carburetor designed to minimize hydrocarbon emmission with substantially no loss in power or performance and with improved economy.

Another object is to provide a high dispersion booster venturi nozzle which is especially designed to vaporize or break up and disperse fuel entering the air in-take passage.

Another object is to provide means for increasing the velocity of air in the air intake passage to achieve better fuel dispersion.

Another object is to provide means for controlling the admission of fuel to the secondary air intake passage designed to prevent premature fuel dumping when the throttle is opened suddenly.

Another ofject is to provide means for balancing the pressures in the primary and secondary fuel chambers to reduce fuel surges in the secondary fuel supply system particularly when the secondary fuel inlet valve opens and closes.

Other objects and features of the invention will become apparent as the following description proceeds, especially when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a top plan view of a carburetor constructed in accordance with my invention but with the primary and secondary air valves omitted so as to expose the venturi boosters in the primary and secondary air intake passages.

FIG. 2 is a front view of the carburetor with parts shown in section and parts in elevation.

Fig. 3 is an enlarged fragmentary top plan view showing a venturi booster.

FIG. 4 is a sectional view taken on the line 44 in FIG. 3.

FIG. 5 is an enlargement of a portion of FIG. 1.

FIG. 6 is an enlarged fragmentary view showing a modified primary intake passage construction in which the booster venturi is eliminated, taken on the line 6-6 in FIG. 7.

FIG. 7 is a sectional view taken on the line 7-7 in FIG. 6.

Referring now more particularly to the drawings, the carburetor is shown as being of the down-draught type but can be used in any position and comprises a housing 1 having a primary system 3 and a secondary system 4. The carburetor is of the four-barrel type although it will be understood that the invention is also applicable to one and two-barrel carburetors.

The carburetor has two primary air intake passages 13F and two secondary air intake passages 135. Only one of the primary intake passages and one of the secondary air intake passages and their associated parts will be described in detail, although it should be understood that the other primary and secondary air intake passages and their associated parts may be the same as those described.

The primary and secondary air intake passages UP and are formed by adjacent vertical bores in the housing I. The passages 13F and 13S are separated by the housing wall 15. The air intake passage UP is controlled by a suitable actuated throttle valve plate 19 therein secured to a pivotal shaft or pin 19. The primary throttle plate 19 is shown at off-idle and may move from off-idle through part throttle to wide open position in which it is disposed substantially vertically in the passages.

The wall of primary air intake passage I3P is provided intermediate its ends with an annular restriction forming a main venturi 20P for the air flow. A booster venturi 2lP, more fully described hereinafter, or greater restriction than the main venturi 20P is dis posed in the throat of the main venturi.

A primary air valve 22P is secured to a pivotal shaft or pin 22' upstream of the throttle plate 19 and booster venturi 2lP adjacent the top of the primary air intake passage 13F. The air valve 22P may move from the closed position illustrated to a fully open substantially vertical position.

The air valve 22? is subject to the depression (vacuum) in the air intake passage and also to the position of the throttle valve 19. A lever 23 is secured to the shaft 19' of the throttle valve 19 and a lever 24 is secured to the shaft 22 of the air valve 22P. A rod 25 is pivoted to lever 23 and has a spring-biased lost motion connection with the lever 24. This lost motion is provided by a pin 26 movable in an arcuate slot 27 in lever 24 which is centered on the axis of pin 22. The pin has an abutment 28 which is slidable on rod 25. A coil spring 29 on rod 25 is compressed between a fixed abutment 30 on the rod and the sliding abutment 28 to impose a yielding bias tending to close the air valve. Nut 31 threaded on the end of rod 25 is to retain abutment 28 and may be threaded either way to change the compression on spring 29. Obviously this yielding bias is reduced or partially relieved by the counterclockwise opening movement of the throttle valve. The yielding bias permits the air valve to move in opening and closing directions in response to changes in the depression (vacuum) in the air intake passage. The slot 27 allows the air valve 22P to move in a closing direction by differential pressure independently of the throttle plate 19.

The primary system also includes a fuel-receiving portion which has a fuel reservoir or chamber 2P. The fuel chamber 2P is a closed chamber being defined in part by a cavity in the housing and in part by a flexible diaphragm 5P which is clamped over an opening in the cavity by a cover plate 9P. The fuel chamber 2P is completely unvented and isolated from the outside atmosphere.

Fuel is admitted to the chamber 2P from a suitable fuel inlet 6P past a fuel control valve 7P. The fuel control valve 7P includes a cylinder 7a having an elongated, axially movable needle valve 7b therein projecting through an orifice 7c. The needle valve 7b had a head 7d adapted to close the orifice and is normally urged to closed position by a calibrated spring AP bearing at one end against the head 7d and at the other end against the wall of the cylinder 7a. The needle valve 7b also has a stem 7e projecting from the head 7d and engageable with the diaphragm 5P. The inlet 6? opens into the interior of the cylinder 7a but fuel from the inlet enters the chamber 2P only when the needle valve 7b is opened by the movement of the diaphragm 5P to the left in FIG. 2.

The primary system 3 has a main jet 23P leading to the fuel passages 24P and 25P. The passage 25P leads to the booster venturi 21P and the passage 24? leads to the idle ports 27 and 28. Idle ports 27 and 28' are open to manifold vacuum in the curb-idle position of the throttle plate 19 to provide a proper fuel mixture. The size of the idle port 28' is controlled by an idle adjustment screw 29P.

The diaphragm SP is exposed to the pressure within the fuel chamber 2P on one side and to atmospheric presssure on the other side, and is movable in response to differential pressure. Movement of the diaphragm 5P to the left in FIG. 2 will move the needle valve 7P to the left and open orifice 70 so that the fuel can flow into chamber 2P.

A mechanical linkage is provided to control the needle valve 7b in response to movement of the throttle valve 19. This linkage is indicated at 46F and includes a lever 47? pivoted at its upper end at 60F to the cover plate 9?. Intermediate its ends, the lever has an abutment 61P engageable with, but not secured to, a member 62P on the outer side of the diaphragm 5P. At its lower end, the lever 47P is pivoted to the outer end of a push rod 48P which extends and slides through an opening in a housing plate lb. The inner end of push rod 48? engages a cam SOP secured to and rotatable with throttle plate shaft 19' so that the cam turns with the throttle plate. A coil spring 64P compressed between the housing plate lb and a flange 63? on push rod 48? holds the inner end of the push rod in contact with the cam 50?. Rotation of the throttle plate 19 will rotate the cam 50F and since the inner end of the rod 48P is in contact with the cam profile, the position of the throttle plate 19 will determine the angular position of the lever 47P.

Referring to the secondary system 4, a secondary throttle plate 365 is secured to a pivotal shaft or pin 36' in the secondary air intake passage 13S adjacent the lower end thereof. Throttle plate 365 is movable from the closed position shown in solid lines to an open substantially vertical position. The primary throttle plate shaft 19 has a lever 33F connected to it, and a lever 355 is connected to the secondary throttle plate 368. One end of a rod 345 is pivoted to the lever 33F and the other end has a slidable pivotal connection in slot 398 in the lever 358 to provide a lost motion connection between the primary and secondary throttle plates.

An air valve 375 secured to pivotal shaft or pin 37 is disposed adjacent the top of the secondary air intake passage 13$ for movement from the closed position shown to an open substantially vertical position. The secondary air valve 378 is normally closed but opens in response to increasing depression (vacuum) in the air intake passage 135. Engine manifold vacuum is applied to the air intake passage 135 when the secondary air valve 368 opens. Depending upon the particular engine requirements, the responsiveness of air valve 375 to differential air pressure, and thus its opening rate can be controlled. It is preferable to avoid sudden snap-like opening of the secondary air valve 375. For this purpose control means are provided to govern or dampen the opening rate of the air valve 378, such control means in this instance being shown as a plurality of pressure relief openings 405 in the air valve which allow air to pass through at a predetermined calibrated rate. This reduces the initial force exerted on air valve 375 when secondary throttle plate 368 is opened, and also provides a controlled initial rate of opening.

There is an annular restriction forming a venturi 205 in passage 13S and a booster venturi 218 in the throat of the venturi 208.

Fuel is supplied to the secondary system from a fuel receiving portion which is substantially the same as the fuel receiving portion previously described and accordingly the same reference numerals with the suffix S instead ofP are employed. Thus the fuel chamber 28 is defined in part by a cavity in the housing and in part by the flexible diaphragm 55 which is clamped over an opening in the cavity by the cover plate 98. The fuel chamber 25 is a completely closed reservoir unvented I to the atmosphere.

The fuel control valve 78 controls the admission of fuel to the chamber,2S from the fuel inlet 68. The parts of this fuel valve 75, namely the portions 7a 7e are the same as those previously described in connection with the fuel valve 7P and function in the same manner, and the needle valve 7b is acted upon by a similar calibrated spring AS.

The secondary system 4 has a main jet 238 leading to fuel passages 24S and 255. The passage 25S leads to the venturi booster S18 and the passage 24S leads to the seondary idle port 51.

The diaphragm SS is exposed to the pressure within the fuel chamber 25 on one side and to atmospheric pressure on the other side, and is movable in response to differential pressure. Movement of the diaphragm 58 to the right in FIG. 2 will move the needle valve 7b of fuel valve 78 to the right and open orifice 7c so that fuel can flow into chamber 28.

The mechanical linkage 46$ for controlling the opening of the needle valve of fuel valve includes the lever 47S pivoted at its upper end at 608 to the cover plate 98, which lever has an abutment 61S spaced from the pivot and engageable with but not connected to the member 628 on the outer side of the diaphragm 58.

The lever 475 has a lost motion connection with the secondary air valve 378. A link 405 is secured to shaft 37 so as to turn with the air valve 378. A rod 418 is pivoted to the link 40S and slides through a sleeve 428 in the lever 475. A compression coil spring 438 encircles the rod between an abutment 448 on the end of the rod and the sleeve 428 on the lever. In the closed position of the air valve 375 shown in FIG. 2, the lost motion connection will hold the lever 478 in substantially the position shown. It will be apparent that counterclockwise opening movement of the air valve will, through the resilient lost motion connection, impose a yielding force on the lever 47S tending to move it counterclockwise and move diaphragm 58 to the right thereby opening the needle valve 7b.

The venturi booster 21P is shown in FIGS. 3 and 4. The venturi booster 218 is of the same construction.

The booster venturi 21P is in the form of a tubular or ring-shaped body having a central through passage 199 aligned with the air intake passage 13P. This passage has a restriction at the upper end providing a venturi 203. A circular channel 200 in the venturi booster encircles the passage 199 at or slightly below the venturi 203 and receives fuel from passage 25P. Small axially extending venturi apertures or openings 201 extend into the channel 200, and axially extending slightly flaring apertures or openings 202, aligned with openings 201, extend downward from the channel 200 into the enlarged exit or skirt portion 198 of the passage 199. Fuel moving around the channel 200 is broken up and dispersed by the fast moving air in openings and 202 and carried into the exit portion 198 of passage 199. The exit portion 198 forms a chamber to merge the discharge of air and dispersed and atomized fuel from openings 202 with the air passing through the booster venturi 203.

Radial aperutres or openings 204 extend horizontally inwardly from channel 200 to provide communication between the channel 200 and the passage 199 adjacent the restriction or venturi 203. The restriction terminates in an annular depending lip 205 which partially overlaps the openings 204 to increase the venturi effect and draw fuel from the channel 200 into the air passage 199 by the depression (vacuum) at this point in the air passage. The fuel drawn into the air passage is dispersed and atomized by the fast moving air in the venturi 203.

It will thus be seen that a high degree of atomization or breakup and dispersion of fuel in the circular channel 200 is achieved. The air moving through the axial openings 201 and 202 carries the dispersed fuel with it into the air intake passage 13P. Simultaneously, air passing through venturi 203, which is the throat of a pezometer ring, also draws fuel by way of the cross-holes 204 into the passage 199. Accordingly, fuel is dispersed by both the vertical passages 20] and 202 and horizontal passages 204 to atomize the liquid fuel into a homogeneous air-fuel mixture.

A fuel line 98 is shown in FIG. 1 having one end 99 adapted to receive fuel from the tank by a fuel pump. The other end of the line which is a return line to the fuel tank has a restriction 100. The fuel inlets 6P and 68 to the fuel chambers communicate in sequence with the fuel line 99. This arangement, including the restriction, reduces the amount of fuel surging in the fuel supply system when the secondary needle valve 7b opens and closes. Also, this arrangement reduces surging on sudden heavy demand when otherwise the secondary system might lag and substantially all of the fuel initially be supplied to the primary system.

A balance tube or passage 10] having a restriction 102 connects the fuel chambers 2P and 28. This arrangement serves to balance pressures in the two chambers and also assists in reducing surges in the fuel supply system when the secondary needle valve 7!) opens and closes. It also assists in eliminating a tendency for the secondary system to lag on sudden heavy demand and all of the fuel initially to go to the primary system.

ln operation, when the engine is turned over during starting, fuel under pressure from the fuel tank and line 98 enters the fuel inlet passages 6P and 6S and fills the passages completely up to fuel valves 7P and 78. The excess fuel passes through restriction and returns to the fuel tank. The primary air valve 22P is normally in a closed position when the engine is not operating and throttle plate 19 is in the curb-like position. Cranking the engine induces a depression (vacuum) which is sensed at idle ports 27, 28' and 51, as well as at the primary venturi booster 21P. This depression (vacuum) is transmitted through the respective channels and passages 24P, 25F and. 248 through the main jets 23P and 238 to the chambers 2P and 28. The depression (vacuum) in chambers 2P and 2S forces the diaphragms SP and 58 to move or flex inwardly pushing needle valves 7b inwardly against the tension of calibrated springs AP and AS, opening the orifices 7c and allowing fuel to flow from the inlets into chambers 2P and 28. The fuel in chambers 2P and 28 is then transmitted through the main jets 23P and 238 to the respective passages 24P, 24S and 25P. Thus fuel initially enters the air stream through idle ports 27, 28' 51 and booster venturi 21?. Fuel does not initially flow from booster venturi 215 because secondary throttle plate 365 and secondary air valve plate 378 are closed at this time.

As the engine idles the primary air valve plate 2P opens slightly, depending on the pre-load and tension of the calibrated primary air valve spring 29 to allow air to enter. The degree of opening of primary air valve 22P is a function of the rate and tension of the spring 29 which is calibrated for specific air demands. The lighter the pre-load and rate of spring 29, the greater the amount of air supplied to the As primary throttle plate 19 opens wider, the primary air valve control rod 25 reduces the tension on spring 29 allowing the primary air valve 22F to open further, leaning out the air-fuel mixture and still maintaining high air velocities.

The provision of the primary air valve 22P maintains high air velocities in the primary system at curb-idle, off-idle and low part-throttle (30-40 miles per hour) engine operations so as to achieve a high degree of fuel vaporization and homogeneity of fuel-air mixtures and the entry of the fuel-air mixture into the cylinders of the engine at high air velocities. As a result, a lean homogeneous mixture is achieved reducing overall pollutant emissions. The primary air valve functions to provide these high air velocities until it reaches a substantially vertical position in the air intake passage, which is at a part-throttle position of the throttle plate 19 where secondary throttle plate 368 begins to open, and is inoperative thereafter.

At the curb-idle position of throttle plate 19, the engine vacuum at idle ports 27', 28' and 51 is high. This high depression (vacuum) is transmitted by the passages 24P, 24S and 25P to the diaphragms SP and 5S and produces a corresponding inward movement thereof. The amount which the diaphragms move at curb-idle is governed by engine depression only and is not controlled through the mechanical linkages 46F and 468.

As the throttle plate 19 is opened wider from curbidle, the movement of air through the air passage 13P draws fuel from the booster venturi 21P. The depression (vacuum) in the fuel passages is further reduced in turn the diaphragms SP and 5S move outward by differential pressure and the needle valves 7b begin to close. However, the mechanical linkage 46P prevents the diaphragm P from moving outward far enough to close the needle valve and maintains a constant linear relationship between the fuel requirements of the engine and the air flow through the carburetor at all positions of the throttle plate 19 other than curb-idle, namely, off-idle, part-throttle and wide-open throttlev For a given position of throttle plate 19 other than curb-idle, a' minimum needle valve position of valve 7P is by mechanically be the action of the linkage 46P. The amount of opening of the needle valve 7b of valve 7P is governed by the profile of cam SOP and the lever ratio of lever 47P.

The rate and amount of opening of the needle valve of valve 7P is transmitted mechanically from the outer or atmospheric side of the diaphragm 5P. This mechanical linkage provides the minumum fuel delivery necessary to operate the engine at the lowest permissible hydrocarbon levels. If the velocity of air passing the booster venturi 21F and the depression (vacuum) at idle ports 27 and 28' should increase to an amount greater than normally encountered at a specific throttle opening, the diaphragm SP is permitted to flex inwardly away from the lever 47P by differential pressure allowing a richer mixture in order to maintain a combustible fuel and air mixture to the engine maintaining a constant power output in relation to air consumption demand. However, the differential pressure acting on the diaphragm cannot lean out or reduce the fuel delivery below that which cam SOP is designed to deliver.

During initial opeing of throttle plate 19, secondary throttle plate 363 remains closed due to the lost motion built into the linkage 33S35S. At an intermediate position of the throttle plate 19P, called the pick-up point, the linkage causes secondary throttle plate 368 to begin to open. By varying the construction of the linkage, the rate of opening of plate 368 relative to plate 19 can be chanbed to provide different fuel-air mixtures at different loads and engine speeds to suit performance requirements.

As secondary throttle plate 368 opens, secondary air valve 375 is subjected to increased downward air pressure tending to open it from its generally closed position. As this occurs, additional air flow is generated through secondary air passage 138. As before stated, control means are provided to govern or dampen the opening rate of the secondary air valve 375, here shown as comprising the relief openings 408. This reduces the initial force on secondary air valve 375 when the secondary throttle plate 368 is open and also provides a controlled initial rate of opening.

The opening of the secondary throttle plate 365 results in an increase in manifold depression (vacuum) transmitted through the secondary venturi booster 21S and passage 258 due to the closed position of the secondary air valve 375. This higher depression is transmitted through the main metering jet 235 to the secondary diaphragm 55. The diaphragm 5S responding to this higher depression (vacuum) moves the secondary needle valve 7b inward to allow additional fuel to enter chamber 28 and then via the main jet 23S and the booster venturi 215 to enter the engine. When the depression (vacuum) below the secondary air valve 378 reaches a sufficient magnitude, the secondary air valve begins to open allowing additional air to enter the secondary air intake 135. The rate of opening of the secondary air valve 375 is a function of the rate and tension of the calibrated spring 435 which opposes such opening movement. The opening of the secondary air valve 378 in turn moves the lever 47S counterclockwise by a yielding pressure applied through spring 438. Such movement of the lever 47S shifts the diaphragm 58 further inwardly to cause needle valve 71) to allow greater amounts of fuel to enter the chamber 28 and ultimately to flow into the secondary air intake passage 218. As secondary air valve 378 continues to open in response to differential pressure, the lever 478 is turned further in a counterclockwise direction by the yielding force of spring 438 to allow even greater amounts of fuel to enter the secondary system.

FIGS. 6 and 7 illustrate a modified primary air intake passage construction in which the booster venturi is eliminated and the main venturi modified to incorporate features of the booster venturi previously described. As there shown, the primary intake passage l3P is formed by a vertical bore in the housing 1 as in FIGS. 1 and 2. The wall of the primary intake passage l3P is provided intermediate its ends with an annular ring-shaped venturi body formation 20P' having a central through passage 299 which is aligned with the air intake passage. This central through passage 299 has a restriction at the upper end providing a main venturi 303. A circular channel 300 in the ring-shaped formation encircles the passage 299 at or slightly below the venturi 303 and receives fuel from passage 25P. Small axially extending venturi apertures or openings 30] extend into the channel 300 and axialy extending flaring openings or apertures 302 aligned with openings 301 extend downwardly from the channel 300 into the primary intake passage l3P beneath the venturi body formation 20P'. Fuel moving around the channel 300 is broken up and dispersed by the fast moving air in openings 301 and 302 and carried into the primary intake passage beneath venturi body formation 20P. The discharge of air and dispersed and atomized fuel from openings 302 is merged with the air passing through venturi 303 in the primary intake passage l3P beneath the venturi body formation 20P.

Radial apertures or openings 304 extend horizontally inwardly from channel 300 to provide communication between the channel 300 and the passage 299 adjacent the restriction or venturi 303. The restriction terminates in an annular lip 305 which partially overlaps the openings 304 to increase the venturi effect and draw fuel from the channel 300 into the air passage 299 by the depression (vacuum) at this point in the air passage. The fuel drawn into the air passage is dispersed and atomized by the fast moving air in the venturi 303.

It will thus be seen that a high degree of atomization or breakup and dispersion of fuel in the circular channel 300 is achieved. The air moving through the axial openings 301 and 302 carries the dispersed fuel with it into the air intake passate l3P beneath venturi body formation 21P'. Simultaneously, air passing through venturi 303, which is the throat of a pezometer ring, also drawsfuel by way of the cross-holes 304 into the passage 299. Accordingly, fuel is dispersed by both the vertical passages 301 and 302 and horizontal passages 304 to atomize the liquid fuel intoa homogeneous airfuel mixture.

It will be understood that the operation of the modified carburetor will be substantially the same as that previously described, except that fuel in passage 25P will flow into the fuel channel 300 of the main venturi rather than into the fuel channel 200 of the booster venturi.

The secondary intake passage construction may if desired be modified to eliminate the booster venturi and alter the main venturi to incorporate the features shown in FIGS. 6 and 7.

What I claim as my invention is:

1. In a carburetor, an air intake passage having an annular restriction forming a main venturi, a booster venturi member disposed in the throat of said main venturi and having a through air passage provided with an annular restriction forming a booster venturi, said booster venturi member having a fuel channel surrounding said through air passage, axially extending venturi apertures opening into said fuel channel to admit air thereinto from the upstream side of said booster venturi member to disperse and atomize fuel in said fuel chamber, and outlet apertures respectively aligned with said venturi apertures and leading from said fuel channel to discharge the air and dispersed and atomized fuel from said fuel channel to the downstream side of said booster venturi member.

2. The structure defined in claim 1, wherein said venturi apertures have extensions extending part way into and terminating in said fuel channels.

3. The structure defined in claim 1, wherein said booster venturi member has a skirt surrounding and extending beyond the discharge ends of said outlet apertures, forming a chamber to merge the discharge of air and dispersed and atomized fuel from said outlet apertures with the air passing through said booster venturi.

4. The structure defined in claim 3, wherein said venturi apertures have extensions extending part way into and terminating in the said fuel channels, and additional apertures which extend radially inward from said fuel channel to said through air passage near said booster venturi.

5. The structure defined in claim 4, wherein said booster venturi is formed by an annular lip which overhangs said additional apertures.

6. In a carburetor, an air intake including means having a through air passage provided with an annular restriction forming a venturi, means providing a fuel channel surrounding said through air passage, axially extending venturi apertures opening into said fuel channel to admit air thereinto from the upstream side of said venturi to disperse and atomize fuel in said fuel channel, and outlet apertures respectively aligned with said venturi apertures and leading from said fuel channel to discharge the air and dispersed and atomized fuel from said fuel channel to the downstream side of said venturi.

7. The structure defined in claim 6, wherein said venturi apertures have extensions extending part way into and terminating within said fuel channels.

8. The structure defined in claim 6, including means providing a skirt surrounding and extending beyond the discharge end of said outlet apertures, forming a chamber to merge the discharge of air and dispersed and atomized fuel from said outlet apertures with the air passing through said venturi.

9. The structure defined in claim 6, wherein said venturi is a main venturi. 

1. In a carburetor, an air intake passage having an annular restriction forming a main venturi, a booster venturi member disposed in the throat of said main venturi and having a through air passage provided with an annular restriction forming a booster venturi, said booster venturi member having a fuel channel surrounding said through air passage, axially extending venturi apertures opening into said fuel channel to admit air thereinto from the upstream side of said booster venturi member to disperse and atomize fuel in said fuel chamber, and outlet apertures respectively aligned with said venturi apertures and leading from said fuel channel to discharge the air and dispersed and atomized fuel from said fuel channel to the downstream side of said booster venturi member.
 2. The structure defined in claim 1, wherein said venturi apertures have extensions extending part way into and terminating in said fuel channels.
 3. The structure defined in claim 1, wherein said booster venturi member has a skirt surrounding and extending beyond the discharge ends of said outlet apertures, forming a chamber to merge the discharge of air and dispersed and atomized fuel from said outlet apertures with the air passing through said booster venturi.
 4. The structure defined in claim 3, wherein said venturi apertures have extensions extending part way into and terminating in the said fuel channels, and additional apertures which extend radially inward from said fuel channel to said through air passage near said booster venturi.
 5. The structure defined in claim 4, wherein said booster venturi is formed by an annular lip which overhangs said additional apertures.
 6. In a carburetor, an air intake including means having a through air passage provided with an annular restriction forming a venturi, means providing a fuel channel surrounding said through air passage, axially extending venturi apertures opening into said fuel channel to admit air thereinto from the upstream side of said venturi to disperse and atomize fuel in said fuel channel, and outlet apertures respectively aligned with said venturi apertures and leading from said fuel channel to discharge the air and dispersed and atomized fuel from said fuel channel to the downstream side of said venturi.
 7. The structure defined in claim 6, wherein said venturi apertures have extensions extending part way into and terminating within said fuel channels.
 8. The structure defined in claim 6, including means providing a skirt surrounding and extending beyond the discharge end of said outlet apertures, forming a chamber to merge the discharge of air and dispersed and atomized fuel from said outlet apertures with thE air passing through said venturi.
 9. The structure defined in claim 6, wherein said venturi is a main venturi. 